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#lang racket/base
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;; Provides the syntax used to create lexers and the functions needed to
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;; create and use the buffer that the lexer reads from. See docs.
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(require (for-syntax racket/syntax
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syntax/stx
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syntax/define
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yaragg/parser-tools/private-lex/util
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yaragg/parser-tools/private-lex/actions
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yaragg/parser-tools/private-lex/front
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yaragg/parser-tools/private-lex/unicode-chars
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racket/base
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racket/promise))
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(require racket/stxparam
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syntax/readerr
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yaragg/parser-tools/private-lex/token)
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(provide lexer lexer-src-pos lexer-srcloc define-lex-abbrev define-lex-abbrevs define-lex-trans
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;; Dealing with tokens and related structures
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define-tokens define-empty-tokens token-name token-value token?
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(struct-out position)
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(struct-out position-token)
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(struct-out srcloc-token)
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;; File path for highlighting errors while lexing
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file-path
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lexer-file-path ;; alternate name
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;; Lex abbrevs for unicode char sets.
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any-char any-string nothing alphabetic lower-case upper-case title-case
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numeric symbolic punctuation graphic whitespace blank iso-control
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;; A regular expression operator
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char-set)
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;; wrap-action: syntax-object src-pos? -> syntax-object
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(define-for-syntax (wrap-action action src-loc-style)
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(with-syntax ([action-stx
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(cond
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[(eq? src-loc-style 'lexer-src-pos)
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#`(let/ec ret
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(syntax-parameterize
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([return-without-pos (make-rename-transformer #'ret)])
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(position-token #,action start-pos end-pos)))]
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[(eq? src-loc-style 'lexer-srcloc)
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#`(let/ec ret
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(syntax-parameterize
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([return-without-srcloc (make-rename-transformer #'ret)])
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(srcloc-token #,action lexeme-srcloc)))]
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[else action])])
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(syntax/loc action
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(λ (start-pos-p end-pos-p lexeme-p input-port-p)
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(define lexeme-srcloc-p (make-srcloc (object-name input-port-p)
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(position-line start-pos-p)
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(position-col start-pos-p)
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(position-offset start-pos-p)
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(and (number? (position-offset end-pos-p))
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(number? (position-offset start-pos-p))
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(- (position-offset end-pos-p)
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(position-offset start-pos-p)))))
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(syntax-parameterize
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([start-pos (make-rename-transformer #'start-pos-p)]
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[end-pos (make-rename-transformer #'end-pos-p)]
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[lexeme (make-rename-transformer #'lexeme-p)]
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[input-port (make-rename-transformer #'input-port-p)]
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[lexeme-srcloc (make-rename-transformer #'lexeme-srcloc-p)])
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action-stx)))))
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(define-for-syntax (make-lexer-macro caller src-loc-style)
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(λ (stx)
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(syntax-case stx ()
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[(_ . RE+ACTS)
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(with-disappeared-uses
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(let ()
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(define spec/re-acts (syntax->list #'RE+ACTS))
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(for/and ([x (in-list spec/re-acts)])
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(syntax-case x ()
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[(RE ACT) #t]
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[else (raise-syntax-error caller "not a regular expression / action pair" stx x)]))
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(define eof-act (get-special-action spec/re-acts #'eof (case src-loc-style
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[(lexer-src-pos) #'(return-without-pos eof)]
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[(lexer-srcloc) #'(return-without-srcloc eof)]
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[else #'eof])))
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(define spec-act (get-special-action spec/re-acts #'special #'(void)))
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(define spec-comment-act (get-special-action spec/re-acts #'special-comment #'#f))
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(define ids (list #'special #'special-comment #'eof))
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(define re-acts (filter (λ (spec/re-act)
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(syntax-case spec/re-act ()
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[((special) act)
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(not (ormap
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(λ (x)
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(and (identifier? #'special)
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(module-or-top-identifier=? #'special x)))
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ids))]
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[_ #t])) spec/re-acts))
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(define names (map (λ (x) (datum->syntax #f (gensym))) re-acts))
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(define acts (map (λ (x) (stx-car (stx-cdr x))) re-acts))
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(define re-actnames (map (λ (re-act name) (list (stx-car re-act) name)) re-acts names))
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(when (null? spec/re-acts)
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(raise-syntax-error caller "expected at least one action" stx))
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(define-values (trans start action-names no-look) (build-lexer re-actnames))
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(when (vector-ref action-names start) ;; Start state is final
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(unless (and
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;; All the successor states are final
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(vector? (vector-ref trans start))
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(andmap (λ (x) (vector-ref action-names (vector-ref x 2)))
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(vector->list (vector-ref trans start)))
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;; Each character has a successor state
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(let loop ([check 0]
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[nexts (vector->list (vector-ref trans start))])
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(cond
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[(null? nexts) #f]
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[else
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(let ([next (car nexts)])
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(and (= (vector-ref next 0) check)
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(let ([next-check (vector-ref next 1)])
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(or (>= next-check max-char-num)
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(loop (add1 next-check) (cdr nexts))))))])))
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(eprintf "warning: lexer at ~a can accept the empty string\n" stx)))
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(with-syntax ([START-STATE-STX start]
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[TRANS-TABLE-STX trans]
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[NO-LOOKAHEAD-STX no-look]
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[(NAME ...) names]
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[(ACT ...) (map (λ (a) (wrap-action a src-loc-style)) acts)]
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[(ACT-NAME ...) (vector->list action-names)]
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[SPEC-ACT-STX (wrap-action spec-act src-loc-style)]
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[HAS-COMMENT-ACT?-STX (if (syntax-e spec-comment-act) #t #f)]
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[SPEC-COMMENT-ACT-STX (wrap-action spec-comment-act src-loc-style)]
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[EOF-ACT-STX (wrap-action eof-act src-loc-style)])
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(syntax/loc stx (let ([NAME ACT] ...)
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(let ([proc (lexer-body START-STATE-STX
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TRANS-TABLE-STX
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(vector ACT-NAME ...)
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NO-LOOKAHEAD-STX
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SPEC-ACT-STX
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HAS-COMMENT-ACT?-STX
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SPEC-COMMENT-ACT-STX
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EOF-ACT-STX)])
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;; reverse eta to get named procedures:
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(λ (port) (proc port))))))))])))
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(define-syntax lexer (make-lexer-macro 'lexer #f))
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(define-syntax lexer-src-pos (make-lexer-macro 'lexer-src-pos 'lexer-src-pos))
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(define-syntax lexer-srcloc (make-lexer-macro 'lexer-srcloc 'lexer-srcloc))
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(define-syntax (define-lex-abbrev stx)
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(syntax-case stx ()
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[(_ NAME RE) (identifier? #'NAME)
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(syntax/loc stx
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(define-syntax NAME
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(lex-abbrev (λ () (quote-syntax RE)))))]
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[_ (raise-syntax-error 'define-lex-abbrev "form should be (define-lex-abbrev name re)" stx)]))
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(define-syntax (define-lex-abbrevs stx)
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(syntax-case stx ()
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[(_ . XS)
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(with-syntax ([(ABBREV ...) (map
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(λ (a)
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(syntax-case a ()
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[(NAME RE) (identifier? #'NAME)
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(syntax/loc a (define-lex-abbrev NAME RE))]
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[_ (raise-syntax-error
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#f
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"form should be (define-lex-abbrevs (name re) ...)"
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stx
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a)]))
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(syntax->list #'XS))])
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(syntax/loc stx (begin ABBREV ...)))]
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[_ (raise-syntax-error #f "form should be (define-lex-abbrevs (name re) ...)" stx)]))
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(define-syntax (define-lex-trans stx)
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(syntax-case stx ()
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[(_ name-form body-form)
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(let-values (((name body)
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(normalize-definition #'(define-syntax name-form body-form) #'λ)))
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#`(define-syntax #,name
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(let ((func #,body))
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(unless (procedure? func)
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(raise-syntax-error 'define-lex-trans "expected a procedure as the transformer, got ~e" func))
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(unless (procedure-arity-includes? func 1)
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(raise-syntax-error 'define-lex-trans "expected a procedure that accepts 1 argument as the transformer, got ~e" func))
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(lex-trans func))))]
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[_
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(raise-syntax-error
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#f
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"form should be (define-lex-trans name transformer)"
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stx)]))
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(define (get-next-state-helper char min max table)
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(cond
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[(>= min max) #f]
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[else
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(define try (quotient (+ min max) 2))
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(define el (vector-ref table try))
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(define r1 (vector-ref el 0))
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(define r2 (vector-ref el 1))
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(cond
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[(and (>= char r1) (<= char r2)) (vector-ref el 2)]
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[(< char r1) (get-next-state-helper char min try table)]
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[else (get-next-state-helper char (add1 try) max table)])]))
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(define (get-next-state char table)
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(and table (get-next-state-helper char 0 (vector-length table) table)))
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(define ((lexer-body start-state trans-table actions no-lookahead special-action
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has-special-comment-action? special-comment-action eof-action) ip)
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(define (lexer ip)
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(define first-pos (get-position ip))
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(define first-char (peek-char-or-special ip 0))
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;(printf "(peek-char-or-special port 0) = ~e\n" first-char)
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(cond
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[(eof-object? first-char)
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(do-match ip first-pos eof-action (read-char-or-special ip))]
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[(special-comment? first-char)
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(read-char-or-special ip)
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(cond
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(has-special-comment-action?
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(do-match ip first-pos special-comment-action #f))
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(else (lexer ip)))]
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[(not (char? first-char))
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(do-match ip first-pos special-action (read-char-or-special ip))]
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[else
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(let lexer-loop (
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;; current-state
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[state start-state]
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;; the character to transition on
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[char first-char]
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;; action for the longest match seen thus far
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;; including a match at the current state
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[longest-match-action
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(vector-ref actions start-state)]
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;; how many bytes precede char
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[length-bytes 0]
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;; how many characters have been read
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;; including the one just read
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[length-chars 1]
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;; how many characters are in the longest match
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[longest-match-length 0])
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(define next-state
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(cond
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[(not (char? char)) #f]
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[else (get-next-state (char->integer char)
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(vector-ref trans-table state))]))
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(cond
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[(not next-state)
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(check-match ip first-pos longest-match-length
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length-chars longest-match-action)]
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[(vector-ref no-lookahead next-state)
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(define act (vector-ref actions next-state))
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(check-match ip
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first-pos
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(if act length-chars longest-match-length)
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length-chars
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(if act act longest-match-action))]
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[else
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(define act (vector-ref actions next-state))
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(define next-length-bytes (+ (char-utf-8-length char) length-bytes))
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(define next-char (peek-char-or-special ip next-length-bytes))
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#;(printf "(peek-char-or-special port ~e) = ~e\n"
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next-length-bytes next-char)
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(lexer-loop next-state
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next-char
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(if act
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act
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longest-match-action)
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next-length-bytes
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(add1 length-chars)
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(if act
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length-chars
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longest-match-length))]))]))
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(unless (input-port? ip)
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(raise-argument-error 'lexer "input-port?" 0 ip))
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(lexer ip))
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(define (check-match lb first-pos longest-match-length length longest-match-action)
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(unless longest-match-action
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(define match (read-string length lb))
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(define end-pos (get-position lb))
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(raise-read-error
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(format "lexer: No match found in input starting with: ~v" match)
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(file-path)
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(position-line first-pos)
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(position-col first-pos)
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(position-offset first-pos)
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(- (position-offset end-pos) (position-offset first-pos))))
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(define match (read-string longest-match-length lb))
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;(printf "(read-string ~e port) = ~e\n" longest-match-length match)
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(do-match lb first-pos longest-match-action match))
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(define file-path (make-parameter #f))
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(define lexer-file-path file-path)
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(define (do-match ip first-pos action value)
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#;(printf "(action ~a ~a ~a ~a)\n"
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(position-offset first-pos) (position-offset (get-position ip)) value ip)
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(action first-pos (get-position ip) value ip))
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(define (get-position ip)
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(define-values (line col off) (port-next-location ip))
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(position off line col))
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(define-syntax (create-unicode-abbrevs stx)
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(syntax-case stx ()
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[(_ CTXT)
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(with-syntax ([(RANGES ...) (for/list ([range (in-list (list (force alphabetic-ranges)
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(force lower-case-ranges)
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(force upper-case-ranges)
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(force title-case-ranges)
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(force numeric-ranges)
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(force symbolic-ranges)
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(force punctuation-ranges)
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(force graphic-ranges)
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(force whitespace-ranges)
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(force blank-ranges)
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(force iso-control-ranges)))])
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`(union ,@(map (λ (x)
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`(char-range ,(integer->char (car x))
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,(integer->char (cdr x))))
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range)))]
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[(NAMES ...) (for/list ([sym (in-list '(alphabetic
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lower-case
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upper-case
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title-case
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numeric
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symbolic
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punctuation
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graphic
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whitespace
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blank
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iso-control))])
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(datum->syntax #'CTXT sym #f))])
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#'(define-lex-abbrevs (NAMES RANGES) ...))]))
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(define-lex-abbrev any-char (char-complement (union)))
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(define-lex-abbrev any-string (intersection))
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(define-lex-abbrev nothing (union))
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(create-unicode-abbrevs #'here)
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(define-lex-trans (char-set stx)
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(syntax-case stx ()
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[(_ STR)
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(string? (syntax-e #'STR))
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(with-syntax ([(CHAR ...) (string->list (syntax-e #'STR))])
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#'(union CHAR ...))]))
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(define-syntax provide-lex-keyword
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(syntax-rules ()
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[(_ ID ...)
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(begin
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(define-syntax-parameter ID
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(make-set!-transformer
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(λ (stx)
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(raise-syntax-error
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'provide-lex-keyword
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(format "use of a lexer keyword (~a) is not in an appropriate lexer action" 'ID)
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stx))))
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...
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(provide ID ...))]))
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(provide-lex-keyword start-pos end-pos lexeme lexeme-srcloc input-port return-without-pos return-without-srcloc)
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